[PATCH -mm 2/2] do_wait-wakeup-optimization: simplify task_pid_type()

[Oleg Nesterov <oleg@redhat.com>]

task_pid_type() is only used by eligible_pid() which has to check
wo_type != PIDTYPE_MAX anyway. Remove this check from task_pid_type()
and factor out ->pids[type] access, this shrinks .text a bit and
simplifies the code.

The matches the behaviour of other similar helpers, say get_task_pid().
The caller must ensure that pid_type is valid, not the callee.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---

 kernel/exit.c |   14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

--- WAIT/kernel/exit.c~2_WAKE_PARENT_ELIGIBLE_FIX_CLEANUP	2009-09-01 12:59:23.000000000 +0200
+++ WAIT/kernel/exit.c	2009-09-01 13:51:15.000000000 +0200
@@ -1096,17 +1096,15 @@ struct wait_opts {
 	int			notask_error;
 };
 
-static struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
+static inline
+struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
 {
-	struct pid *pid = NULL;
-	if (type == PIDTYPE_PID)
-		pid = task->pids[type].pid;
-	else if (type < PIDTYPE_MAX)
-		pid = task->group_leader->pids[type].pid;
-	return pid;
+	if (type != PIDTYPE_PID)
+		task = task->group_leader;
+	return task->pids[type].pid;
 }
 
-static inline int eligible_pid(struct wait_opts *wo, struct task_struct *p)
+static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
 {
 	return	wo->wo_type == PIDTYPE_MAX ||
 		task_pid_type(p, wo->wo_type) == wo->wo_pid;